Cement-fiber board



@ein 269 w43., A. ELMENDQRF gmvm@ CEMENT-FIBER BOARD Filed Oct. 26,1940' Patented oci. ze, *.1943

UNITED STATES PATENT OFFICE CEMENT-FIBER BOARD Armin 'Elmenaorawinnetka., 1u. Application October 26, 1940, Serial No. 362,951

11 claims. (c1. 15a-45.9)

greatly restricted, due both to their great thickness and to their greatweight. The object of the present invention is to produce a board orpanel of this general type which is light and thin and yet of sufficientstrength to permit it successfully to be used for facing walls orceilings, as a plaster base, and as a sound-absorbing material, incompetition with other materials employed for these same purposes.

In accordance with my invention, I use fibers that are fine orthread-like instead of coarse, as is the case with ordinary excelsior.This enables me, in the iirst instance, to secure what may be regardedas a more finely grained product. One side of each panel is reenforcedwith a sheet of strong, tough, exible material, preferably kraft paper,bonded or united to the panel by a layer of cement. Inorganic cements,in general, and preferably hydraulic cements, are suitable for mypurpose. When the paper and the porous body are bonded together by alayer oi' inorganic cement, the panel remains flat whereas, if thebonding material be organic, it warps badly. The body of a panel, somade, is of a skeleton-like structure full of interconnected large poresor cavities. Therefore, although the paper and the cement reenforcing onone face seal the pores or cavities on one side of the-panel, the poreson the opposite side remain open. When a panel is placed against a wallin the interior of a building, with the backing next to the wall, thebacking best serves its intended purpose oi providing tensile strengthto resist bending oi the panel under thrusts against the exposed face.At the same time, the exposed side or face is best adaptto bind thepaper to the porous body is that if the paper lies upon a smooth, iiatsurface during the making of a panel, the paper-faced side of the panelwill not only be at but smooth and free from depressions. 'I'his is dueto the fact that the cement fills the pores in the under face of theporous mass andsets in the form of a hard layer Whose under surfacetakes on the smoothness of the iiat supporting surface. Therefore, thepaper-coated face of the panel may be exposed in situations where asmooth, at surface is desired. When an organic binder is used, on theother hand, the paper facing contains pits and presents a roughappearance because it shows the iibrous nature of the underlyingstructure.

While vegetableflbers of other kinds may be employed, I prefer wood ber.Some wood fibers may be coated directly with the cement. In orderfurther to increase the strength of the board or panel, the iibersmay begiven a preliminary treatment to provide them with a coating of calciumsilicate.

The cement sets promptly on fibers of cottonwood, poplar, aspen, whitepine, and ponderosa pine, amongA others, without such preliminarytreatment. Other woods as, for example, red- Wood and oak, do notcooperate satisfactorily, in their natural states, with the cement whichdoes not set properly on them in their natural states. I have discoveredthat if the fibers of such Woods are boiled and then washed until theirwater-soluble elements are leached therefrom, they may be handled injust the same way as are those of woods that require no preliminarytreatment.

In the manufacture of panels, thread-like wood fibers, say, aboutone-nitieth of an inch in transverse dimensions, and preferably not overan inch or two long, are dampened. The cement, which may be ordinaryPortland cement, is dusted over the mass of wet fibers. The mass is thenrun through a shredder which thoroughly agitates and mixes the fibersand delivers them in what may be termed a iiuffy condition. Backingsheets of the proper size of the panels desired having been prepared,these are moistenedl both for the purpose of insuring that they will liefiat, and for the further purpose of protecting cement that comes incontact therewith from having too much water withdrawn therefrom byabsorption in the backing material. A thin layer of cement,

' in a plastic state, is then spread over each backing sheet. Thebacking sheet may inthe first instance have been placed in the bottom ofa mold or form, or the mold or form may be placed about the same afterthecoating or layer of cement has been applied. The proper quantity ofshredded or fibrous material in which the individual fibers carry moistcement coatings is then deposited in the form or mold associated witheach backing sheet and is distributed to give a uniform thickness ordepth throughout the en tire area of the form or mold. A suitable platenor presser member is then brought down'upon the fibrous mass which issqueezed until the fibrous material has been reduced to a layer of thedesired thickness. The pressure on the work is maintained until thecement has taken an initial set, whereupon the slabs or panels areremoved from the forms or molds and are stackedl up so that the moisturewill be retained within the same while the curing of the cementproceeds. After standing thus for several days, the slabs or panels areplaced in a drier from which they emerge ready for use.

For coating the bers, I use from two to three g parts, by weight, of drycement to one part, by

cement layer or coating for the backing sheet is of a thickness thatresults from the application of a slush containing from about onehundred pounds to three hundred pounds of cement for each one thousandsquare feet of the sheet backing material. If the backing material is akraft paper having a thickness of about ten one-thousandths of an inch,the cement coating should be about twice as thick as the paper, althoughthat factor is variable.

Panels may, of course, be manufactured in various sizes. What may betermed a popular.

size is a panel twenty and one-quarter inches wide and sixty-four incheslong.

Some of the desirable characteristics of my lmproved panels are:although unbalanced in construction, they do not warp; they do notshrink or expand in drying or wetting; they will not support combustion;they will not crack and can be nailed and sawed; they have greatstrength, considering their lightness; they have good soundabsorbingcapacity; they may be painted for decorative effects and, if thepainting is done by spraying, their sound-absorbing properties are notdiminished; and they may advantageously be employed as a plaster base,since plaster keys itself thereto exceedingly well.

In the accompanying drawing, 1 is a perspective view of a panelembodying the present invention; Fig. 2 is an elevational view of theface of the panel showing, on a. much larger scale than Fig. 1, afragment of one corner of the panel; Fig. 3 is a section. on a magnifiedscale, on line 3 3 of Fig. 2; Fig. 4 is a perspective view, on a stilllarger scale, of a fragment of one of the coated fibers; and Fig. 5 is aview similar to Fig. 3, showing a modification.

Referring to the drawing, I represents a cement coated thread-likestrand comprising a thread-like element 2 of wood, although othervegetable fiber may be employed; the element 2 being coated withinorganic cement 3. 4 is a thin slab composed-of nbers or strands Idisposed haphazardly and united into a rigid, porous structure by theircement coatings. 5 is a backing sheet, for which tough kraft paper issuitable.

Voverlying the backing sheet andsecurely bonded thereto is a thin layer6 of inorganic cement which is integrated with the slab-like porous bodymember.

In the process of manufacturing the panel, as heretofore described, thefiuied mass of fibers, haphazardly disposed, is compressed, whileoverlying the coated backing sheet, to a small fraction of its originalthickness, while the cement coating on the backing and the coating onthe bers are still wet, so that when the cement sets,

the panel becomes a hard, rigid body full of pores or cavities, thoseadjacent to one face of the panel opening out through that face, whilethose on the opposite side of the panel are sealed by the cement layer 6and the backing sheet 5. The backing sheet and the cement layer orcoating thereon form the only imperforate part of the structureextending across the entire length and width of the panel, and thereforeconstitute an effective tension member for the panel when the latter isin its normal position of final use.

It is, of course, evident that should one desire to do so, boards orpanels may be faced with paper on both sides. In that case, a layer ofcement may be applied over the board or panel before it is removed fromthe mold or form, a sheet of paper be laid on the cement and pressure beexerted through a flat top plate. Such a structure is shown in Fig. 5,wherein the panel of Fig- 3 is shown as having on the upper side addedlayers 1 and 8 correspondingto the layers 6 and 6 on the bottom.

It will of course be understood that although the paper faced panelsconstitute the most highly developed form of my invention, the paperfacing or facings may be omitted and still leave the panel with noveland valuable properties', namely, atness and smoothness and hardness ofsurface. Also, in the case of a panel such as shown in Fig. 5, the paperfacing may be retained on the tension side of the panel and be omittedon the compression side.

While I have'illustrated and described with particularity only a fewphysical embodiments of my invention, I do not desire to be limited tothe exact structural details thus illustrated and described, nor to theexact details of the method dlsclosed; but intend to cover all forms andmethods coming within the definitions of my invention constituting theappended claims,

I claim:

1. A panel for structural purposes comprising a paper backing, a layerof inorganic cement forming a coating on one side of the backing and amass of cement-coated haphazardly-disposel fibers united by theircoatings into a skeletonlike, porous structure permanently united tosaid coating.

2. A panel for structural purposes comprising a paper backing, a. layerof inorganic cement forming a coating over one face of said backing, anda thin, rigid slab, composed of cementcoated vegetablel fibers looselymatted and held together by their coatings, integrally united with saidcoating; the cement layer' being sufficiently thick to hold the panelnat against the pull of the paper backing, upon drying.

3. A panel for structural purposes having a thickness of one-half inchor less comprising a thin, flexible backing sheet, a. coating ofinorganic cement bonded to the backing sheet, and a porous slab composedof matted fibers coated with and united to each other by inorganiccement, said slab and said coating being permanently united; the said.coating of cementbeing about twice as thick as the backing sheet.

4. A panel for structural purposes comprising a flexible backing sheet,a layer of inorganic cement forming a coating on one side of the backingsheet, andamass of cement-coated haphazardly-disposed wood bers having awidth in the neighborhood of one flftieth of an inch united by theircoatings into a skeleton-like porous structure permanently joined to thecoating on the hacking sheet.

5. A panel for structural purposes comprising a iexible backing in theform of kraft paper about one-hundredth of aninch thick or the like, alayer of inorganic cement about one-nftieth of an inch thick forming acoating over one face of said backing, and a thin, rigid slab, composedof cement-coated Wood fibers having widths of about one-fiftieth of .aninch loosely matted and held together by their coatings, integrallyunited with said coating on the backing.

6. A panel for structural purposes having a thickness of one-half inchor less comprising a exible backing sheet of kraft paper or the like,y

a layer of inorganic cement about one-fiftieth of an inch thick forminga coating on the backing sheet, and a porous slab composed ofthread-like wood fibers coated with and united to each other byinorganic cement, said slab and said coating on the backing sheet beingintegrally united.

'1. A panel for structural purposes comprising a skeleton-like porousslab formed of haphazardly-disposed vegetable bers coated with and heldtogether by inorganic cement, and 'a continuous layer of inorganiccement extending over at least one of the faces of the slab.

8. A panel for structural purposes comprising a thin skeleton-likeporous slab formed of haphazardly-disposed vegetable fibers coated withand held together by inorganic cement, and a thin hard layer ofinorganic cement extending' over aface 0I' and a short distance into thepores of the slab and providing the slab with a smooth surface.

9. A panel for structural purposes comprising a thin skeleton-likeporous slab formed of 'haphazardly-disposed vegetable fibers vcoatedwith and held together by inorganic cement, andv a thin hard layer ofinorganic cement extending over each face of and a short distance intothe pores of the slab and providing the slab with smooth surfaces.

10. A panel for structural purposes comprising a skeleton-like porousslab formed of hap-` hazardly-disposed vegetable bers coated withinorganic cement and held together by their coatings, the weight of theaforesaid cement being greater than that ofthe vegetable bers, when bothare dry, and a continuous layer of inorganic cement extending over atleast one of the faces of the slab and penetrating a short distance intothe interior of the slab at that face.

il. A panel for structural purposes comprising a skeleton-like porousslab formed of haphazardlydisposed vegetable iibers coated with aninorganic cement which, in a dry state, has a weight at least twice asgreat as the weight of the dry vegetable iibers, said fibers being heldto each other by their coatings, and a continuous layer of inorganiccement extending over at least one face o the slab.

ARMIN' EINIIEIIIDORF.

